Heat oven to 325°F. Coat baking sheets with vegetable cooking spray. In large bowl, with mixer on medium, beat egg whites until foamy. Increase to high and beat in sugar until peaks form, about 3 minutes. Beat in flour, vanilla, and salt. Reserve 1 cup coconut. Stir remainder into egg-white mixture.
Scoop heaping tablespoons of mixture onto baking sheets. Gently press in centers and sprinkle with reserved coconut. Bake 25 to 30 minutes, or until lightly browned.